The purpose of this research is to identify the role of specific structural proteins in the assembly of lipoprotein membranes. The lipoprotein envelope of vesicular stomatitis virus is used since it affords a system in which specific membrane proteins may be readily identified and envelope assembly may be studied in the infected cell. Our recent studies have concerned the association of newly synthesized viral envelope proteins with cellular membranes in an attempt to identify structural features of these proteins necessary for this association.